The lawsuit comes six months after several other retailers filed a similar suit alleging delays in getting a generic version of Effexor XR onto store shelves, and brings the total of chains suing the world's largest drugmaker about this matter to eight. Among the other retailers suing the pharmaceutical giant: Walgreen Co., Kroger Co. and Safeway Inc.

In a complaint filed with the federal court in Trenton, N.J., CVS and Rite Aid accused the Wyeth unit of conspiring to block generic versions for at least two years after its marketing rights lapsed in June 2008. Tactics the pharmacies accuse Wyeth of include: fraudulent patents, sham litigation and scheming with Teva to keep cheaper generics off the market.

Pfizer and Teva had no immediate comment, Reuters said. Effexor XR accounted for $129 million in global sales in the first quarter of 2012 -- down 37 percent from a year earlier.

New York-based Pfizer, which has some 2,950 employees in Kalamazoo County, is one of the largest businesses in the area.

Yvonne Zipp is a business reporter for the Kalamazoo Gazette. You can reach her at yzipp@mlive.com or 269-365-8639.